1. Field of the Invention
This invention relates to a head suspension for supporting a head of a disk device, to a disk device which uses it, and to a testing method for a head IC.
2. Description of the Related Art
Disk devices for reading a disk storage medium using a head are widely used. For example, magnetic disk drives that are used as storage devices for computers comprise a magnetic disk, a spindle motor that rotates the magnetic disk, a magnetic head for reading from or writing to the magnetic disk, and a VCM actuator that positions the magnetic head at a track on the magnetic disk.
The storage density of these kinds of disk drives is greatly increasing, as well as is the density of tracks on the magnetic disk. It is especially possible to increase the density by using a MR (GMR, TMR) head as the magnetic head. Therefore, a high precision device is also desired for processing of the head signal.
In a magnetic disk device, the magnetic head is supported by a suspension. The suspension is attached to the carriage arm of a VCM actuator. The suspension has springiness and functions such that the magnetic head follows the surface of the magnetic disk. The magnetic head performs input/output of an analog signal, so it is equipped with a head IC for processing the analog signal. The head IC comprises a preamp for amplifying the read signal of the magnetic head, and a writing amp for supplying writing current to the magnetic head.
Normally, this head IC is attached to the carriage arm located at the rear of the suspension. Moreover, the head IC is connected to the magnetic head by lead wires on the suspension. However, in the case of a weak magnetic head output, as in the case of the recent MR heads, it is not possible to ignore the effect of noise that mixes into the long lead wire.
In addition, when the lead wire is long, the rising time and falling time of the pulse signal (writing pulse) both become long, so there is a problem in that it becomes difficult to transfer data at high speed. Therefore, it is proposed to place the head IC chip on the suspension in order to shorten the distance between the magnetic head and the head IC.
With that kind of construction, it is necessary to test each suspension. Conventionally, a slider on which the head IC and magnetic head are located is attached to the suspension to form a HGA (head gimbal assembly), then this HGA is made to float above the disk medium and by the head magnetically reading/writing, the operation of the head IC and the connection status are checked.
However, with the prior method, the head and head IC of the HGA unit are checked together so when one is determined to be faulty that entire HGA is considered faulty. Therefore, there is a problem that yield decreases and it is difficult to keep costs down.